net/sched/em_nbyte.c

   1 /*
   2  * net/sched/em_nbyte.c N-Byte ematch
   3  *
   4  *              This program is free software; you can redistribute it and/or
   5  *              modify it under the terms of the GNU General Public License
   6  *              as published by the Free Software Foundation; either version
   7  *              2 of the License, or (at your option) any later version.
   8  *
   9  * Authors:     Thomas Graf <tgraf@suug.ch>
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/types.h>
  14 #include <linux/kernel.h>
  15 #include <linux/sched.h>
  16 #include <linux/string.h>
  17 #include <linux/skbuff.h>
  18 #include <linux/tc_ematch/tc_em_nbyte.h>
  19 #include <net/pkt_cls.h>
  20
  21 struct nbyte_data
  22 {
  23         struct tcf_em_nbyte     hdr;
  24         char                    pattern[0];
  25 };
  26
  27 static int em_nbyte_change(struct tcf_proto *tp, void *data, int data_len,
  28                            struct tcf_ematch *em)
  29 {
  30         struct tcf_em_nbyte *nbyte = data;
  31
  32         if (data_len < sizeof(*nbyte) ||
  33             data_len < (sizeof(*nbyte) + nbyte->len))
  34                 return -EINVAL;
  35
  36         em->datalen = sizeof(*nbyte) + nbyte->len;
  37         em->data = (unsigned long) kmalloc(em->datalen, GFP_KERNEL);
  38         if (em->data == 0UL)
  39                 return -ENOBUFS;
  40
  41         memcpy((void *) em->data, data, em->datalen);
  42
  43         return 0;
  44 }
  45
  46 static int em_nbyte_match(struct sk_buff *skb, struct tcf_ematch *em,
  47                           struct tcf_pkt_info *info)
  48 {
  49         struct nbyte_data *nbyte = (struct nbyte_data *) em->data;
  50         unsigned char *ptr = tcf_get_base_ptr(skb, nbyte->hdr.layer);
  51
  52         ptr += nbyte->hdr.off;
  53
  54         if (!tcf_valid_offset(skb, ptr, nbyte->hdr.len))
  55                 return 0;
  56
  57         return !memcmp(ptr + nbyte->hdr.off, nbyte->pattern, nbyte->hdr.len);
  58 }
  59
  60 static struct tcf_ematch_ops em_nbyte_ops = {
  61         .kind     = TCF_EM_NBYTE,
  62         .change   = em_nbyte_change,
  63         .match    = em_nbyte_match,
  64         .owner    = THIS_MODULE,
  65         .link     = LIST_HEAD_INIT(em_nbyte_ops.link)
  66 };
  67
  68 static int __init init_em_nbyte(void)
  69 {
  70         return tcf_em_register(&em_nbyte_ops);
  71 }
  72
  73 static void __exit exit_em_nbyte(void)
  74 {
  75         tcf_em_unregister(&em_nbyte_ops);
  76 }
  77
  78 MODULE_LICENSE("GPL");
  79
  80 module_init(init_em_nbyte);
  81 module_exit(exit_em_nbyte);